Holding devices of this type are often required in performing surgical procedures in order to hold medical instruments of many kinds, such as retractors, video cameras or endoscopes, in a certain position for an extended period. Because of the jointed configuration of the holding devices it is possible for the surgeon to precisely position the medical instrument held by the bracket and to secure the selected position of the holding device by blocking the joint or joints of the bracket.
To be able to supply electric current and/or a pneumatic or hydraulic pressure means to the medical instruments affixed on the holding device, and/or parts of the holding device itself such as the locking devices to secure and release the joints of the bracket, it is standard practice in the art to direct lines through the interior of the bracket and also through the joints that removably connect the bracket parts with one another.
A generic holding device with lines fed through the ball and socket joint is known, for example, from DE 295 21 305 U1. To protect the lines from becoming twisted or otherwise damaged by the pivoting motion of the joints, the ball and socket joints of this known holding device comprise a pivot guard by which the pivoting angle of the joints around their longitudinal axis can be restricted, for example prevented from pivoting by more than 360 degrees. This known pivot guard consists of a surrounding groove configured in the pivot ball as well as a pivot guard ring that is positioned on the pivot ball at a right angle to the surrounding groove and is mounted in the surrounding groove by pins pointing radially inward. As a result, a movement of the pivot ball, by the pins engaging in the surround groove, generates a pivoting movement of the pivot guard ring around the longitudinal axis of the joints. To restrict the pivot angle, a pin is positioned at a distance toward the outside and, in the event of pivoting by the guard ring, comes into contact with a guard pin configured as a backstop, which in turn is firmly mounted in the bearing shell of the ball and socket joint.
With this known structure it is possible to restrict the pivot angle of the joint in such a way that the lines fed through the joint are protected; however, this known structure also has the problem that, in the event of diagonal movements of the pivot ball, in particular with simultaneous pivoting movement around the longitudinal axis of the joint, the system can jam or the joints can become stiff through friction of the pins on the surface of the pivot ball or of the pivot guard ring in the guide track. In addition this known structure has the disadvantage of requiring considerable construction space around the pivot ball.
Consequently it is the object of the invention to provide a holding device for medical instruments of the aforementioned type whose pivot guard makes possible a compact structure of the ball and socket joint.